The present invention relates to a system for detecting abnormality for an automotive engine.
Japanese Utility Model Application Laid-Open No. 60-141442 discloses a system for detecting abnormality in an output control system in which a throttle valve of an engine is operated by a stepper motor in accordance with the degree of depression of an accelerator pedal. The system is provided with a control unit for controlling the engine. The control unit is applied with input data such as output torque detected at the transmission of the vehicle, engine speed detected by a speed sensor, an intake-air quantity, and a coolant temperature, and determines whether the engine is normally controlled or not. In this system, the operation of the engine is monitored by the control unit based on the input data. If the output torque does not increase with an increase of the intake air, the engine is deemed abnormal. In the engine, if trouble in the intake system occurs for example by clogging of an intake passage with a foreign substance, the output torque does not increase in spite of a wide open throttle. However, the system does not detect such trouble because the detected output torque corresponds to a small amount of the intake air.